Editing Eta Carinae (section)

===Potential supernova===
[[File:Supernovae as initial mass-metallicity.svg|upright=1.6|thumb|alt=Regions on the two-dimensional chart show what kind of supernovae or white dwarfs result from different stars.|Supernovae types depending on initial mass and metallicity]]
The overwhelming probability is that the next supernova observed in the Milky Way will originate from an unknown [[white dwarf]] or anonymous [[red supergiant]], very likely not even visible to the naked eye.<ref name="adams">{{cite journal|doi=10.1088/0004-637X/778/2/164|title=Observing the Next Galactic Supernova|journal=The Astrophysical Journal|volume=778 |issue=2|pages=164|year=2013|last1=Adams|first1=Scott M.|last2=Kochanek|first2=C. S.|last3=Beacom|first3=John F.|last4=Vagins|first4=Mark R.|last5=Stanek|first5=K. Z. |bibcode=2013ApJ...778..164A|arxiv = 1306.0559 |s2cid=119292900}}</ref> Nevertheless, the prospect of a supernova originating from an object as extreme, nearby, and well studied as η&nbsp;Carinae arouses great interest.<ref name="mckinnon">{{cite journal |bibcode=2014AAS...22340503M |title=Eta Carinae: An astrophysical laboratory to study conditions during the transition between a pseudo-supernova and a supernova |journal=[[American Astronomical Society]] |volume=223 |page=#405.03 |last1=McKinnon |first1=Darren |last2=Gull |first2=T.R. |last3=Madura |first3=T. |year=2014}}</ref>

As a single star, a star originally around 150 times as massive as the Sun would typically reach core collapse as a [[Wolf–Rayet star]] within 3 million years.<ref name="groh2013"/> At low metallicity, many massive stars will collapse directly to a [[black hole]] with no visible explosion or a sub-luminous supernova, and a small fraction will produce a [[pair-instability supernova]], but at solar metallicity and above, there is expected to be sufficient mass loss before collapse to allow a visible supernova of [[Type Ib and Ic supernovae|type Ib or Ic]].<ref name="hegar">{{cite journal |last1=Heger |first1=A. |last2=Fryer |first2=C.L. |last3=Woosley |first3=S.E. |last4=Langer |first4=N. |last5=Hartmann |first5=D.H. |title=How Massive Single Stars End Their Life |journal=The Astrophysical Journal |volume=591 |issue=1 |pages=288–300 |year=2003 |bibcode=2003ApJ...591..288H |arxiv=astro-ph/0212469 |s2cid=59065632 |doi=10.1086/375341}}</ref> If there is still a large amount of expelled material close to the star, the shock formed by the supernova explosion impacting the circumstellar material can efficiently convert [[kinetic energy]] to [[radiation]], resulting in a [[superluminous supernova]] (SLSN) or [[hypernova]], several times more luminous than a typical core collapse supernova and much longer-lasting. Highly massive progenitors may also eject sufficient [[nickel]] to cause a SLSN simply from the [[radioactive decay]].<ref name="avishay">{{cite journal |last=Gal-Yam |first=A. |title=Luminous Supernovae |journal=Science |volume=337 |issue=6097 |pages=927–932 |year=2012 |pmid=22923572 |bibcode=2012Sci...337..927G |arxiv=1208.3217 |s2cid=206533034 |doi=10.1126/science.1203601}}</ref> The resulting remnant would be a black hole, for it is highly unlikely such a massive star could ever lose sufficient mass for its core not to exceed the limit for a [[neutron star]].<ref name="SmithOwocki2006">{{cite journal |title=On the Role of Continuum-driven Eruptions in the Evolution of Very Massive Stars |last1=Smith |first1=Nathan |last2=Owocki |first2=Stanley P. |journal=The Astrophysical Journal |volume=645 |issue=1 |pages=L45 |date=2006 |bibcode=2006ApJ...645L..45S |arxiv=astro-ph/0606174 |s2cid=15424181 |doi=10.1086/506523}}</ref>

The existence of a massive companion brings many other possibilities. If η&nbsp;Carinae A was rapidly stripped of its outer layers, it might be a less massive WC- or WO-type star when core collapse was reached. This would result in a type Ib or type Ic supernova due to the lack of hydrogen and possibly helium. This supernova type is thought to be the originator of certain classes of gamma-ray bursts, but models predict they occur only normally in less massive stars.<ref name="groh2013"/><ref name="sana"/><ref name="claeys">{{cite journal|bibcode=2011A&A...528A.131C|title=Binary progenitor models of type IIb supernovae|journal=Astronomy & Astrophysics|volume=528|pages=A131|last1=Claeys|first1=J. S. W. |last2=de Mink|first2=S. E.|author2-link=Selma de Mink|last3=Pols|first3=O. R.|last4=Eldridge|first4=J. J.|last5=Baes|first5=M.|year=2011|doi=10.1051/0004-6361/201015410|arxiv = 1102.1732|s2cid=54848289}}</ref>

Several unusual supernovae and impostors have been compared to η&nbsp;Carinae as examples of its possible fate. One of the most compelling is [[SN 2009ip]], a blue supergiant which underwent a [[supernova impostor]] event in 2009 with similarities to η&nbsp;Carinae's Great Eruption, then an even brighter outburst in 2012 which is likely to have been a true supernova.<ref name="2009ip">{{cite journal|bibcode=2014MNRAS.438.1191S|title=SN 2009ip and SN 2010mc: Core-collapse Type IIn supernovae arising from blue supergiants |journal=Monthly Notices of the Royal Astronomical Society|volume=438|issue=2|pages=1191|last1=Smith|first1=Nathan|last2=Mauerhan|first2=Jon C.|last3=Prieto|first3=Jose L. |year=2014|doi=10.1093/mnras/stt2269|doi-access=free |arxiv = 1308.0112|s2cid=119208317}}</ref> SN 2006jc, some 77 million light-years away in UGC 4904, in the constellation [[Lynx (constellation)|Lynx]], also underwent a supernova impostor brightening in 2004, followed by a magnitude 13.8 type Ib supernova, first seen on 9 October 2006. η&nbsp;Carinae has also been compared to other possible supernova impostors such as [[SN 1961V]] and [[iPTF14hls]], and to superluminous supernovae such as [[SN 2006gy]].